A cryptocurrency is a digital coin, designed to be transferred between people in virtual transactions. Cryptocurrencies exist only as data and not as physical objects; you cannot actually hold a Bitcoin in your hand or keep Ethereum in your safe. Owning a Bitcoin means you have the collective agreement of each and every computer on the Bitcoin network that it is currently owned by you and – more importantly – that it was legitimately created by a miner.
TIP: There are a few sides to cryptocurrency. 1. you can trade and invest in it, 2. you can use it for transactions (anywhere a coin type is accepted), 3. you can break out a graphics processing unit and some software and mine coins (see how to mine coins), 4. you can develop for it, etc. All those and more are valid and interesting ways to interact with the crypto space, but with that in mind, this page is focused on “trading” cryptocurrency (and therefore also investing in it). With that said, even if you want to do the other things with cryptocurrencies, you still need to be set up for trading (as for example most miners will sell at least some of the coins they mine and developers will need to fund their operations).
I strongly suggest only seriously entertaining the top say 100 coins by market cap. I personally rarely consider an investment in any coin that isn’t roughly in the top 10 – 20 (there are some rare exceptions, such as with ICOs, but I’m never putting the bulk of my investable funds in anything without proven staying power and community in almost every case).
The first decentralized cryptocurrency, bitcoin, was created in 2009 by pseudonymous developer Satoshi Nakamoto. It used SHA-256, a cryptographic hash function, as its proof-of-work scheme. In April 2011, Namecoin was created as an attempt at forming a decentralized DNS, which would make internet censorship very difficult. Soon after, in October 2011, Litecoin was released. It was the first successful cryptocurrency to use scrypt as its hash function instead of SHA-256. Another notable cryptocurrency, Peercoin was the first to use a proof-of-work/proof-of-stake hybrid.